What characterizes fast-twitch muscle fibers?

Fast-twitch muscle fibers are specifically adapted for short bursts of high-intensity activity, such as sprinting or weightlifting. These fibers possess a greater ability to generate force quickly, which allows for powerful, explosive movements. However, this capability comes with the drawback of rapid fatigue; they tire quickly when used for extended periods.

This characteristic makes fast-twitch fibers ideal for activities that require strength and speed over short durations, rather than sustained efforts. Hence, they are crucial in sports and exercises that demand quick, intense energy expenditure, aligning with the selected answer.